Industry is aware of the desire of protecting against the consequences of a rupture in a fluid line in a fluid system, especially where the load supported by the system is available for acting upon a system such as by falling or otherwise moving when the fluid pressure is lost in the system. One prior art example of a system which has apparatus useful for resisting a load in a lifted position when hydraulic pressure is lost is shown in U.S. Pat. No. 2,964,016.
The present invention provides an arrangement for protecting a hydraulic system against runaway operation in the event of inadvertent loss of hydraulic pressure, such as caused by the rupture of a hydraulic line. The present invention can also be utilized to stop leakage of fluid from the system, and, in the present instance, it operates by sensing fluid flow to and from a fluid motor or a powered cylinder assembly or the like. In the instance of employing a powered fluid cylinder in the fluid system, the flow of fluid to and from the opposite ends of the cylinder is in a fixed proportion therebetween. Accordingly, the present invention provides a protective valve which senses that flow, and if the flow is no longer in that fixed proportion, then the valve acts to block the flow from either end of the cylinder and to thereby avoid the escape of fluid from the system and to avoid the extension or contraction of the cylinder which is commonly subjected to the weight or effort of the load which the system is supporting.
Accordingly, the present invention provides a protective fluid system whereby the escape of fluid from a fluid motor, including a powered fluid cylinder assembly, can be checked so that the load supported by the system will not fall or move or otherwise act upon the system. That is, in the event a fluid line ruptures in the system, or in the event fluid pressure is otherwise sharply reduced in the fluid cylinder assembly, the system of this invention senses that change of fluid pressure and reacts to hold the fluid pressure in the cylinder assembly and to thereby prevent the load supported by the assembly from falling or the like.
In accomplishing the aforementioned objectives and achieving the purposes and advantages mentioned, the present invention does so with a system which incorporates a protective valve which is relatively simple and does not require any complicated working parts and is therefore a fully reliable valve and thus provides an effective and efficient protective system, for the purposes mentioned.
Still further, the present invention provides a fluid protective system which is versatile in its manner in which it protects the various elements and fluid lines in the system, and yet the particular protective valve incorporated in the system is of a reliable and relatively uncomplicated structure, and the protective valve is capable of being incorporated in the system in conjunction with a normally-utilized control valve which controls the flow of fluid to and from the several elements incorporated in the system, such as the fluid pump and the fluid motor or powered cylinder assembly. Further, the present system could incorporate a warning buzzer, light, or other signal which would indicate to the operator that the line has ruptured or that the system has otherwise experienced a rapid loss of fluid pressure.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.